Apparatus for promoting mold growth



Patented dirty 5.27, iwi@ APPARATUS FOR PROMOTING MOLD GROWTH Leo M.Christensen, Moscow, Idaho, assigner to National Agrol Company, Inc.,New York, N. Y., a corporation of Delaware Application October 7, 1940,Serial No. 360,205

7 Claims.

This invention relates generally to a method and apparatus for theproduction of iermentable carbohydrates from starchy materials, and moreespecially to a method and apparatus for facilitating the growth ofmolds on solids substrates of brous character to secure diastatic orother enzymic preparations.

In the manufacture of alcohol from starchif materials, it is necessaryto convert the starch to fermentable carbohydrates prior to the actualalcoholic fermentation operation. Ordinarily this is accomplished by theuse of diastatic material, such as barley malt. However, it is wellknown that the alcohol yields obtained from carbohydrates converted inthis manner have been only about 85% of that theoretically possible fromthe starchy material employed, and this failure to obtain larger yieldshas been attributed to the inability of the enzyme system of suchdiastatic material to convert all of the starch to fermentablecarbohydrates.

Moreover, barley malt is unsatisfactory because of its high cost. Sincegood barley malt must be made from the highest grade barley, and sincethe process of manufacture requires a long factory operation duringwhich the chance for spcilage of the barley is a serious matter, thiscost cannot be reducedand the cost of the manufacture of alcohol iscorrespondingly increased.

In addition to barley malt, other diastatic preparations have beenemployed. For example, Takamine (J. Ind. Eng. Chem. 6, 824, 1914)employed a preparation made by growing selected strains of Aspergillusoryzae on wheat bran. This is an adaptation of the Japanese method forthe manufacture of alcoholic beverages from rice. More recently Fulmer,Underkofler and co-workers (Ind. Eng. Chem. 32,544 (1940) and ibid.31,734 (1939)) have reported studies using the same type ofsaccharifylng agent. In some cases the mold bran was used as I the solesaccharlfying agent, while in others it was used in combination withother diastatic materials, such as barley malt, soybeans, or bacterlalextracts.

Ordinarily, the mold bran is employed in the same manner as barley maltin saccharication, the bran mold being used in the proportion of onepart of bran mold to seven or nine parts of grain on a dry basis. Thealcohol yields obtained from grain treated in this manner have been onthe average a little better than those secured by the use of averagequality barley malt and as good as those secured with the best barleymalt. Therefore, the advantage secured 1n the use of mold bran has beenprincipally derived from the lower cost of diastatic preparation.

Customarily the mold bran is produced by moistening wheat bran witheither water or dilute acid, sterilizing the mixture in a suitablepressure vessel, cooling, and then inoculating with the spores of themold. The material is then placed in an apparatus which is designed toremove the heat produced by the oxidation taking place during the growthof the mold.

Hitherto, for this purpose a tray equipped with a perforated bottomthrough which air may be introduced if needed or a rotating drumprovided with air circulation has been used. Either of these apparatushas been found satisfactory in the production of mold bran in small lotsof one hundred pounds or less, but they have been found to beunsatisfactory in large scale Operations. For eample, when the tray isemployed, the cost of handling the materials and the large number oftrays needed has been a. serious handicap. 0n the other hand, if arotating drum is used, the shearing action involved in the movement ofthe bran has had a detrimental effect upon the growth of the mold, thenewly formed mycelium being torn by the movement Vof the bran. Moreover,by thus reducing the mold growth, the danger ol contaminating themixture with undesirable bacteria which are not damaged by thismechanical action is likely to have an adverse effect upon the growth ofthe mold.

The above mentioned diiliculties in the production of mold bran in largescale operations has proved a serious handicap in the use of suchdiastatic materials in the commercial production of alcohol from starchymaterials. This accoimts for the fact that these materials have onlybeen employed satisfactorily in the laboratory or in small scaleoperations.

One of the objects of this invention is to avoid the above mentioneddilllculties of the prior art.

Another object of this invention is to provide an apparatusV designedfor facilitating the growth of molds on solid substrates of ilbrous ma.-terial, such as wheat bran, in order to secure diastatic orother enzymicpreparations.

Still another object of this invention is to provide an apparatuscomprising a table provided with sections designed to facilitate thecontinuous sterilization, cooling, and inoculation of fibrous materiall'to produce molds.

Yet another object of this invention is to provide a method of growingmolds on solid substrates of fibrous character Without disturbance ofthe growth of the mycelium.

A further object of this invention is to provide a method of producingmolds on solid substrates of fibrous character by means of which thefibrous material is sterilized, cooled and inoculated and the molds areincubated in a continuous operation.

With these and other objects in view, this invention embraces broadly anapparatus and method for producing mold on fibrous material in largequantities without the necessity for handling present when trays areused and Without danger of retarding the growth of the myceliuni as isthe case when a rotating drum is employed.

In the present process, the sterilization, cooling and inoculation ofthe bran or other fibrous material and the incubation of the molds iscontinuous and may be either with or without aeration. Moreover, in thisprocess, by the use of this apparatus higher temperatures can beemployed than are usually permissible, thus increasing the rate andamount of mold growth and thereby correspondingly increasing thediastatlc value of the end product.

The single sheet of drawings discloses diagrammatically one apparatuswhich may be used in practicing the process.

In practicing the process, the wheat bran or other fibrous material ismixed with water or preferably with dilute acid to which nutrient salts,such as zinc, copper or iron sulphate, may be added. Although water maybe used alone, preferably sufficient water is added to give the bran amoisture content of. from 4o to 76%, this water containing sufficienthydrochloric or lactic acid to produce a hydrogen ion concentration offrom Il to 4.2.

The treated bran is then packed loosely in a drag' link conveyor on atable which conveys it to a. sterilization oven where it is heated to atem vperature of from 100 to il0 C. for a period of from thirty to sixtyminutes. If desired, a lower temperature and a corresponding longerperiod of heating may be employed.

The sterilized bran is then conveyed to a cooling section. Ordinarily,fifteen minutes of aeration is sumcient to reduce the temperature of thematerial to approximately C. The rate of aeration to produce the rate ofcooling required to obtain this temperature can be either regulatedmanually or by thermostatic control.

' After approximately ifteen minutes o cooling,

the table is moved to another position where the mold spores are addedand mechanically mixed by any suitable method with the sterile moistbran. During this operation,- the spores may be added in a suspension ofwater or dilute salt solution if desired but preferably they are addedin dry form.

The inoculated bran is then packed into a suitable container, such as adrag link, and is carried over the table through a-section which is notequipped for aeration. Preferably, this section is of sufficient lengthto require twelve hours for the transfer of the inoculated bran over it.

After this period of incubation without aeration, the material issubjected to aeration. The air used may or may not be sterilized ormoistened. The required degree of aeration is secured by the use of airunder a pressure about one inch of water.

In order to provide or variations in bran composition, this pressure.may varied eit e manually or by therniostatio control to meet therequirements. At this stage it is desirable to n- Of) as compared. witha value oi i.. een lo aeaaeae maintain a temperature or" from 40 to 45C. a though usually the bran will not be damaged until the temperatureexceeds approximately 50 C.

The bran is subjected to this incubation period for approximately twelvehours and, after which, the mold mycelium has formed mat which holds thebran in a solid piece. T is .formation makes it impossible to maintaina. suitable ternperature.

For this reason, the bran mold is broken into pieces approximately oneinch in diameter and this material is introduced into suitable appa--ratus, such as a rotating drum or a belt and tunnel unit, provided withadequate air circulation to maintain a suitable temperature. Ii the branhas dried out excessively, it be moistened at this point by sprayingwith water.

The mold bran is aerated in this manner foi' approximately twenty-fourhours when itis ready for. use either in its present 'form or mixedwater to produce a slurry. if desired the product may also be ground.Moreover, if the prod uct is to oe stored, it should be dried first inorder to prevent deterioration.

The bran mold prepa described has a higher made in the tray or druiddescribed even when small scale employed. For example, easily held athigher than ti.

eratione 'loolax 1c r ty :in this proc made by the usual tra-y or Thisthat or completely sacche starch as compared 'with iitee. method.Moreover, danger or" conta almost wholly eliminated and the practicallyautomatic and continu in order to illustrate an app? of carrying outthis process, l.' in the drawing an apparatus, cated. by the numeral i,which ooi container 2 and a separate cantan the acid salt solution.These connected by conduits rotating; dr

a, controlled suitable valves d', to a mixer t where ingredients arethoroughly mingled by me "cal action. The impeller shaft of the ni isdriven by pulley 5 from a suitable outside duree oi por which is notshown. The ap'pwatus provided with two tables t and Mounted on the tableis a ster provided with steam inlet and ou il and a cooling chamberthrough is also Mounted on opposite extremities or ta l are shafts i2and iii upon winch are rigidly .mounted a pressing roll 13 and a carrierroll respectively. These rollers support a continuous linl; it which isdriven by an outside source of power through the pressing roll id. Thelink 'fi is adapted to pass through the oven and cham-- ber lil.

Mounted on the table "l is an incubating nel 2e and an aerating tunnelEl thro air may be 'forced by a suitable pair ci shaf opposite e;rollers 25 mounted a co signed 'to The continuo 2S v.' ich gear l'iltunugh. wh? h by the asaasoe conduit @t in which is mounted a mingler 3lthe impeller blades of which are driven by a pulley 32. The mingler 3lis connected to a source of supply of mold spores by a conduit 33 inwhich is mounted a fan 3d.

Attached to the table i adjacent the roller 25 is a platform 35 on whichis mounted a shaft 35 which carries a roller tl' provided with crushinggrooves 38. The platform 35 also conm nects the table l to a rotary drum3S, the opposite extremity of which empties into a suitable storagecontainer which is not shown. in operation, after the controlledproportions of bran and acid salt solution are thoroughly mixed in 'themingler' t the material passes under the roller lil Where it is tightlypacked. It then passes onto: the drag link iii and is slowly carriedthrough the oven t in which the temperature has been raised by 'the useof steam to a range of from 100 to 110 C. Ordinarily the speed of thedrag link it is regulated so that it requires from thirty to sixtyminutes for the material to pass over this section of the table.

this point the material passes through cooling chamber lil where thetemperature is reduced to apprz'ximately 35 C. Ordinarily this sapproximately fifteen minutes and the material is than conveyed to theend of the table Where it 1s red by gravity through the conduit to themingler At this point the material cornes in contact with the moldspores which are blown into the ...iingler il through the conduiy theaction or fan material is then thoroughly mixed and is gradually forcedunder the press-Y roll upon the drag link fil',

The drag link fil conveys the material through the incubating tunnel Th"section is ci such. length that twelve hours rc required for 'thetransit or t.. e inocuiated oran. et this point the aerating tunnel andthe mateis subjected to aeration, thereby remet ria? ine' th lient gene'ced oxidation during the growth ci" n', i. ring t ls operation the isintr" ader pressure by the ian the i o is controlled to provide 'vi s inthe bran composition. This stage also for approximately twelve hours anda temperature of less than 5Go C. and pref erably be Neen a0 and 45 ismaintained.

this period of incubation, a suiicient mat oi' mycclium is formed tohold the bran in a solid piece. The growth of this material prevents thepassage or sufficient air and therefore gradually permits thetemperature to rise above the desired level. accumulation of heat, the.material by the link to the platt broken into suitable i .inch diameterroiler into either the rotar-J or second tunnel unit for aeration es theturu'iel 2i.

After this additional aeration for approximate y twenty-four hours, thematerial is then trans- ,ed to a temporary storage From this is can cwhere it is rired, may be added z fin order to prevent this Y invention.Moreover, variations in the types of nutrient salts added to the branmaterial and the length of the periods of treatment are contemplated.

It is therefore understood that the invention is to be limited only bythe prior art and the scope of the appended claims.

l' claim:

1. An apparatus for facilitating the growth of molds on solid substratesof brous character comprising a pair of supporting members, a continuousrotatable link, a sterilizing oven, and a cooling tunnel mounted on oneof the supporting members, said link being adapted to pass through thesaid oven and tunnel, an incubating and an aerating tunnel, and acontinuous rotatable link mounted on the second supporting member, saidlink being adapted to pass through the said tunnels, means to rotate thesaid continuous links, and means operatively connecting the twosupporting members to transport the material from the rst to the secondlink.

2. An apparatus for facilitating the growth of molds on solid substratesof brous character comprising, a movable link, a sterilaing oven and acooling tunnel, said link being designed to transport the fibrousmaterial through the said oven and tunnel in the order named, anincubating and aerating tunnel and a second movable link, said linkbeing adapted to transport the ibrous material through the said tunnelsin the order named, means to actuate the continuous links, meansoperatively connecting the said links and designed to transport thematerial from the first to the second link after it has been transportedthrough the cooling tunnel, and means to inoculate material With moldspores during its passage i'f'oln the cooling to the aerating tunnel.

3. .fin apparatus for facilitating the growth of molds on solidsubstrates of fibrous character comprising means to mix a fibrousmaterial and a liquid together, and means to promote the rowth oi moldupon the fibrous material, said second means comprising a link, asterilizing oven and a cooling tunnel, said link being designed totransport the brous material through the said oven and tiffnnel in theorder named, an incubating and aerating tunnel and a second continuouslink, said links being adapted to transport the fibrous material throughthe said tunnels in the order n lined, a single means to rotate thecontinuous link, a conduit operatively connecting the said links anddesigned to transport the mate rial irorn the first to the second linkafter it has been transported through the cooling tunnel, and means toinocuiate the material "with mold spores during its passage through thesaid conduit.

An apparatus for facilitating the growth of .molds on solid substratesof i'ibrous character comprising means to mia a fibrous material and aliquid together, and means to promote the growth of mold upon thefibrous material, said second 'leans comprising a rotatable link, asterilizing oven and a. cooling tunneLfsaid link being designed totransport the brousrfnaterial through the said oven and tunnel in theyorder named, an in hat iL aerating tunnel and a second con- *d linkbeing adapted to transport A f' ie material from after .it beentranstunnel, means to iiil .mii mold spores during its passage thc-ghthe said conduit, and means to reduce the material in. size and furtheraerate the material after :It .has been transported through the aeratingtunnel by the second link, said reducing and aerating means beingoperatively associated with the second link so as to form a continuousoperating unit.

5. An apparatus for facilitating the growth of molds on solid substratesof fibrous character comprising a continuous means to transport thematerial at a predetermined rate and a series of sections through whichthe transporting means is designed to carry the material, said sectionsbeing designed to sterilize, cool, incubate and aerate the 'material inthe order named, means to provide the proper conditions of temperatureand atmosphere to the said sections, and means to inoculate the materialwith mold spores after it has passed the cooling section and before ithas entered the incubating section.

6. An apparatus for facilitating the growth of CTI aeaasee molds onsolid substrates of fibrous chA "ester comprising a rotatable link fortransp-orti ie fibrous material, a series of enclosed serl ons throughwhich the link is designed to pass, means designed to providesterilizing, cooling, incubating, and aerating conditions in thesections in the order named, means between the cooling and theincubating sections to inoculate the material with mold spores and meansto actuate the said linkL '7. An apparatus for facilitating the growthoi molds on solid substrates of brous character comprising a movablelink, a sterilizing oven and a cooling tunnel, said link being designedto transport the fibrous material throughthe said'- oven and tunnel inthe order named, and an incubating and aerating tunnel and a second mov.able link, said link being adapted to transport the) brous materialthrough the said tunnels in the order named and means to actuate thesaid links.

LEO M. CrLRLSENSEN.

